Hitherto, fly traps have been reused repeatedly, so that, even though they are emptied of the dead flies therein, they nevertheless usually contain eggs or maggots which subsequently hatch out, so that the repeatedlyreused trap remains contaminated. Moreover, often a week elapses between successive garbage collections, during which period more maggots or eggs contained in the discarded contents of the trap hatch into more flies which excape to breed again.